One gas is not the other. One cubic meter of gas can produce more energy than the other cubic meter of gas. That's why you don't always pay the same for a cubic meter of gas. You can see that on your electricity bill. There the number of cubic meters used is multiplied by a factor that depends on the so-called "calorific value". This value depends on the geographical origin of the gas and its chemical composition and is not the same for all gases. The majority of natural gas is methane (75-99% by volume). It also contains Ethane (1-15 vol.%), Propane (1-10 vol.%), Butane and other gases.

How is this checked?

The composition of the natural gas and thus the energy value vary. In the Netherlands, the gas supplied to the customer is measured in m³. To compensate for differences in the energy value, the supplied natural gas is recalculated to a standard calorific value. You will find the energy value (or calorific value) of the supplied gas on the gas company's invoices. The testing of solid and liquid fuels concerning determining the calorific value with a bomb calorimeter and calculating the calorific value is carried out according to DIN 51900.

The basis is that the energy value is defined as the amount of water that can heat a given fuel from 14.5 to 15.5 ° C (at standard air pressure and full combustion). 1 gram of water with 1 degree heating is 1 calorie. A calorie is an obsolete unit. Nowadays, a joule is used. 1 calorie equates to 4.1868 joules.

Low caloric and high caloric

The quality of the gas is determined by the calorific value. The calorific value indicates how much energy 1 m³ natural gas contains. Both high-calorific gas (H-gas) and low-calorific gas (L-gas or G-gas) are produced in the Netherlands.

Low calorie

The Groningen field contains natural gas with a low calorific value. This sets it apart from most other parts of the world. This is because the gas contains relatively much nitrogen, namely 14%. This low-calorie natural gas has become the standard for gas stoves and boilers. Not only in the Netherlands, but also in Belgium, Germany and Northern France.

Calorie-rich

High-calorific gas contains much less nitrogen. More energy can therefore be obtained from this gas. In the Netherlands, high-calorific gas mainly occurs in small gas fields on land and at sea. In addition, high-calorific gas is transported from Russia and Norway to the Netherlands. If high-calorific gas is intended for private use, it must be mixed with the quality of the low-calorific G gas. This can be done, for example, by adding nitrogen, which lowers the calorific value.

Pearls of Wisdom

The properties of gas are specified by the Wobbe index:

Calorific value (ΔH)
Wobbe index (W)

W = ΔHs / √d

with
d = relative density = ρgas / ρair
S = standard conditions

The Wobbe index determines the economic value of natural gas and is a construction detail for natural gas burners.

Global trade

The different calorific values are certainly not new. It is actually the basis for a very lively international trade in gas: high-quality gas (high-calorie gas or H-gas), for example, is transported from the Netherlands to countries that need it. Inferior gas (lean gas, L gas) is bought back cheaper. And virtually all gas trading in the wider region, including the North Sea, takes place via the Netherlands.

From the gas meter to the bill

The meter reading of your gas meter is corrected to the calorific value and (if necessary) to the temperature and height:

• The calorific value is the amount of energy of a cubic meter of gas. The national, independent network operator determines the calorific value of the supplied gas every month.
• The amount of gas delivered depends on the temperature in your gas meter. If your measuring instrument does not correct the temperature of the supplied gas, the gas supplier will correct this with a standard factor.
• The volume of the gas supplied depends on the height. Height means the height above NAP, so above sea level. Depending on the height above NAP, the energy supplier corrects this by a factor.
• You can see the sum of these factors under "Your consumption in the past period" in the "Factor" column.

If gas with a lower calorific value is supplied, the price per cubic meter will be lower at the end of the year. And if gas with a higher calorific value was supplied, the price per cubic meter at the end of the year will also be higher.